How to Lower the pH of Water

After testing the water, if the water has a high pH then it is alkaline. Water with a high pH can have serious effects, whether you’re using it for drinking or supplying it to a pool, aquarium, or watering plants. For example, aquarium water with a high pH can make fish sick. In the pool, high pH will cause irritation to the skin and eyes. Fortunately, you have several ways to lower the pH of your water.

Table of Contents

Drinking water

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Squeeze lemon juice into a glass of water to adjust the pH every time you drink water. If you don’t want to treat the water at the source and don’t mind drinking lemon-flavored water, you can add 2-3 drops of lemon juice to a glass of water. Lemon juice is acidic, so it will lower the pH of the water. ^{[1] X Research Source}

You can also drop a slice of lemon into the water if you want a stronger lemon flavor.
Using pure citric acid will have the same effect.

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Install a water filter at the faucet to lower the pH of the water source. Water filters work by removing minerals from the water that cause an increase in pH, including sodium, fluoride, and potassium. Depending on the brand, the filter can be installed by screwing on the faucet. When you turn on the faucet, the filter lowers the pH of the water. ^{[2] X Research Source}

You can find a water filter at any convenience store or supermarket.
A home water filter can filter about 40 liters of water per hour. ^{[3] X Research Sources}

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Lowers the pH of large quantities of water with food acids. Food acids such as phosphoric acid, sulfuric acid and lactic acid are often used when a certain recipe, such as fermentation, requires the use of water with a low pH. The ratio of acid to water depends on the type of acid used and the pH you want to achieve, so read the information on the packaging carefully. ^{[4] X Research Sources}

These products are usually sold in places that supply fermentation or brewing products.

Do you know? You may be surprised by adding acid to water, but acids create harmless compounds when neutralized. Be sure to read product labels and use acids correctly!

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Install an acid pump system to fix the problem. The acid pump system helps balance the pH by measuring the pH as the water comes out from the source. The system then injects food acid into the water to balance the pH as the water exits the faucet. The acid pump system must be installed by a professional, and you will need to work with a local water treatment professional if you choose this option. ^{[5] X Research Sources}

The cost of the system and installation can be up to $ 1500 (in the US), but if your water source has a pH problem, this is an effective solution. ^{[6] X Research Source}

Water for watering plants

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Find out what water pH your plant needs. Before looking for ways to lower the pH of your water, you must know if your plants need an acidic or alkaline environment. Some cultivars such as rhododendrons and sweet potatoes require an acidic environment. However, other cultivars, including wisteria and sugar beets prefer a neutral or slightly alkaline medium. ^{[7] X Trusted Source University of Vermont Department of Plant and Soil Science Go to source}

Most cultivars grow well with a pH of 5.5 – 7.0.

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Squeeze the lemon juice into the watering can. If you add 0.5 ml of lemon juice to 3.5 liters of water, the pH will decrease by about 1.5 units. Lemon juice can be used immediately when squeezed or stored in a bottle, but must be 100% pure. ^{[8] X Research Sources}

You can also use citric acid instead of lemon juice, but it needs to be mixed with a little water first.
If you are going to test the water again, stir the water tank well and wait about 5 minutes to make sure the lemon juice is evenly distributed.

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Add vinegar to the water. Measure out about 15 ml of pure white vinegar and pour it into 4 liters of water. The acidity of vinegar will help neutralize the alkalinity of the water, lowering the pH from 7.5 – 7.7 to about 5.8 – 6.0. ^{[9] X Research Source}

The pH of vinegar is 2-3 and that of lemon juice is 2, so their effects with water are similar. ^{[10] X Research Source}

Pool water

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Quick adjustment of pH with muriatic acid. Muriatic acid or hydrochloric acid is commonly used to lower the pH of pool water. Depending on the acid product you buy, you can either add the acid directly to the pool or dilute it in a bucket before pouring it into the pool. When pouring muriatic acid into the lake, you should hold the can of acid near the surface of the water so that the acid does not splash back on you. You can also add acid to the back stream so that it circulates throughout the tank faster, and make sure the discharge port on the water flows towards the bottom of the lake. ^{[11] X Trusted Source State of Indiana Go to Source}

Muriatic acid is sold at pool supplies stores.
Read product labels carefully to find out how much muriatic acid to add to your tank.
Give less than the recommended amount and wait 4 hours before testing again. Add more acid if needed.

Warning: Muriatic acid and sodium bisulfate are corrosive chemicals. Be sure to read and follow the instructions on the packaging. Work in a well-ventilated area, wearing gloves and goggles. After adding muriatic acid to the pool, wait at least 4 hours before using the pool.

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Sodium bisulfate is the milder solution. Sodium bisulfate is usually in the form of granules, depending on the manufacturer’s instructions, you will either add it directly to the tank or must dissolve it in a bucket before pouring it into the tank. Sodium bisulfate helps to stabilize the pool water’s pH after it has decreased, so it is a better choice in terms of long-term maintenance. ^{[12] X Trusted Source State of Indiana Go to Source}

While it’s still a dangerous chemical, sodium bisulfate isn’t as strong as muriatic acid. However, it doesn’t have a quick effect and often lowers the overall alkalinity of the pool below what you would like.
Use the information on the package and the measured pH value to determine the amount of sodium bisulfate supplied to the aquarium.
Sodium bisulfate is also sold at pool supplies stores.

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Install a _CO2 system in the pool to create a long-term balance. Some _CO2 systems are fully automated, meaning it will monitor the lake water pH and add _CO2 to lower the pH if needed. Some systems operate manually, which means you need to monitor pH daily and adjust _CO2 flow as needed. You should talk to a pool professional to find out which system is right for you. ^{[13] X Research Source}

These systems cost anywhere from $300 to over $10,000 (in the US), depending on the functionality you want, but are more economical than having to buy pH balancing chemicals.

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Test pH at least twice weekly with the test kit. The chemicals used in the pool will get out of balance if you don’t pay close attention, so you should test the pH of your pool water about 2-3 times per week, even after you have balanced the pH. You can use Litmus-branded pH test paper if you want, but a DPD test kit will give more accurate results. This test kit measures your water’s overall pH and alkalinity, along with the chlorine level in your tank, so you can balance all of these at once. ^{[14] X Trusted Source Centers for Disease Contrp and Prevention Go to source}

Oils from human skin, sunscreen, lotions, and dirt can throw off the pH balance in the pool. If the pool is used every day then you should check the pH daily.
pH test kits are sold at pool supplies stores.

Fish tank water

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Install a CO ₂ aerator to temporarily lower the aquarium water pH. Installing a _CO2 aerator in the tank can cause a slight, rapid effect in pH reduction, so it is a good option if the pH suddenly rises. However, _CO2 is expensive and the pH will return as soon as aeration is stopped, so this is not a long-term solution. ^{[15] X Research Source}

You can find _CO2 at any aquarium supply store.

Warning: Adjusting aquarium water pH too quickly can shock fish. To avoid this, remove the fish from the tank before lowering the pH.

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Install a reverse osmosis filter system for large aquariums. The reverse osmosis filtration system works very effectively, can remove 99% of the impurities from the water but leaves behind beneficial ions for the fish. Since dirt is the cause of the increase in pH, the pH will automatically decrease as the filtration system works to clean the water. ^{[16] X Research Source}

The cost for this filter system can be up to $ 50 (in the US) and takes up a lot of space, so it is only suitable for large aquariums.

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Add driftwood to the aquarium to naturally filter the water and for decoration. Besides the decorative function of the aquarium, driftwood can also filter water. Just a small piece of driftwood will help lower and stabilize the pH of the aquarium water. In addition, that log is also an interesting place for fish to explore.

Driftwood can sometimes change the color of the water. To avoid this, you should soak the driftwood in a bucket of water for several days before adding it to the aquarium.
Don’t put driftwood used in reptile tanks in your aquarium. It may have been laced with chemicals that would leak into the water and kill the fish.
A small piece of driftwood can also filter the aquarium water, so you should choose a log size that matches the landscape in the tank.

Steps

Drinking water

Water for watering plants

Pool water

Fish tank water

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